pihelp: fat.c comparison

comparison fat.c @ 19:5f9a40d6991b

Import SD handling from http://www.roland-riegel.de/sd-reader/index.html Use smaller build options

author	Matt Johnston <matt@ucc.asn.au>
date	Tue, 25 Jun 2013 13:55:11 +0800
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-:021e6e0006f4
+:5f9a40d6991b
+/*
+* Copyright (c) 2006-2012 by Roland Riegel <[email protected]>
+*
+* This file is free software; you can redistribute it and/or modify
+* it under the terms of either the GNU General Public License version 2
+* or the GNU Lesser General Public License version 2.1, both as
+* published by the Free Software Foundation.
+*/
+#include "byteordering.h"
+#include "partition.h"
+#include "fat.h"
+#include "fat_config.h"
+#include "sd-reader_config.h"
+#include <string.h>
+#if USE_DYNAMIC_MEMORY
+#include <stdlib.h>
+#endif
+/**
+* \addtogroup fat FAT support
+*
+* This module implements FAT16/FAT32 read and write access.
+*
+* The following features are supported:
+* - File names up to 31 characters long.
+* - Unlimited depth of subdirectories.
+* - Short 8.3 and long filenames.
+* - Creating and deleting files.
+* - Reading and writing from and to files.
+* - File resizing.
+* - File sizes of up to 4 gigabytes.
+*
+* @{
+*/
+/**
+* \file
+* FAT implementation (license: GPLv2 or LGPLv2.1)
+*
+* \author Roland Riegel
+*/
+/**
+* \addtogroup fat_config FAT configuration
+* Preprocessor defines to configure the FAT implementation.
+*/
+/**
+* \addtogroup fat_fs FAT access
+* Basic functions for handling a FAT filesystem.
+*/
+/**
+* \addtogroup fat_file FAT file functions
+* Functions for managing files.
+*/
+/**
+* \addtogroup fat_dir FAT directory functions
+* Functions for managing directories.
+*/
+/**
+* @}
+*/
+#define FAT16_CLUSTER_FREE 0x0000
+#define FAT16_CLUSTER_RESERVED_MIN 0xfff0
+#define FAT16_CLUSTER_RESERVED_MAX 0xfff6
+#define FAT16_CLUSTER_BAD 0xfff7
+#define FAT16_CLUSTER_LAST_MIN 0xfff8
+#define FAT16_CLUSTER_LAST_MAX 0xffff
+#define FAT32_CLUSTER_FREE 0x00000000
+#define FAT32_CLUSTER_RESERVED_MIN 0x0ffffff0
+#define FAT32_CLUSTER_RESERVED_MAX 0x0ffffff6
+#define FAT32_CLUSTER_BAD 0x0ffffff7
+#define FAT32_CLUSTER_LAST_MIN 0x0ffffff8
+#define FAT32_CLUSTER_LAST_MAX 0x0fffffff
+#define FAT_DIRENTRY_DELETED 0xe5
+#define FAT_DIRENTRY_LFNLAST (1 << 6)
+#define FAT_DIRENTRY_LFNSEQMASK ((1 << 6) - 1)
+/* Each entry within the directory table has a size of 32 bytes
+* and either contains a 8.3 DOS-style file name or a part of a
+* long file name, which may consist of several directory table
+* entries at once.
+*
+* multi-byte integer values are stored little-endian!
+*
+* 8.3 file name entry:
+* ====================
+* offset  length  description
+*      0       8  name (space padded)
+*      8       3  extension (space padded)
+*     11       1  attributes (FAT_ATTRIB_*)
+*
+* long file name (lfn) entry ordering for a single file name:
+* ===========================================================
+* LFN entry n
+*     ...
+* LFN entry 2
+* LFN entry 1
+* 8.3 entry (see above)
+*
+* lfn entry:
+* ==========
+* offset  length  description
+*      0       1  ordinal field
+*      1       2  unicode character 1
+*      3       3  unicode character 2
+*      5       3  unicode character 3
+*      7       3  unicode character 4
+*      9       3  unicode character 5
+*     11       1  attribute (always 0x0f)
+*     12       1  type (reserved, always 0)
+*     13       1  checksum
+*     14       2  unicode character 6
+*     16       2  unicode character 7
+*     18       2  unicode character 8
+*     20       2  unicode character 9
+*     22       2  unicode character 10
+*     24       2  unicode character 11
+*     26       2  cluster (unused, always 0)
+*     28       2  unicode character 12
+*     30       2  unicode character 13
+*
+* The ordinal field contains a descending number, from n to 1.
+* For the n'th lfn entry the ordinal field is or'ed with 0x40.
+* For deleted lfn entries, the ordinal field is set to 0xe5.
+*/
+struct fat_header_struct
+{
+offset_t size;
+offset_t fat_offset;
+uint32_t fat_size;
+uint16_t sector_size;
+uint16_t cluster_size;
+offset_t cluster_zero_offset;
+offset_t root_dir_offset;
+#if FAT_FAT32_SUPPORT
+cluster_t root_dir_cluster;
+#endif
+};
+struct fat_fs_struct
+{
+struct partition_struct* partition;
+struct fat_header_struct header;
+cluster_t cluster_free;
+};
+struct fat_file_struct
+{
+struct fat_fs_struct* fs;
+struct fat_dir_entry_struct dir_entry;
+offset_t pos;
+cluster_t pos_cluster;
+};
+struct fat_dir_struct
+{
+struct fat_fs_struct* fs;
+struct fat_dir_entry_struct dir_entry;
+cluster_t entry_cluster;
+uint16_t entry_offset;
+};
+struct fat_read_dir_callback_arg
+{
+struct fat_dir_entry_struct* dir_entry;
+uintptr_t bytes_read;
+#if FAT_LFN_SUPPORT
+uint8_t checksum;
+#endif
+uint8_t finished;
+};
+struct fat_usage_count_callback_arg
+{
+cluster_t cluster_count;
+uintptr_t buffer_size;
+};
+#if !USE_DYNAMIC_MEMORY
+static struct fat_fs_struct fat_fs_handles[FAT_FS_COUNT];
+static struct fat_file_struct fat_file_handles[FAT_FILE_COUNT];
+static struct fat_dir_struct fat_dir_handles[FAT_DIR_COUNT];
+#endif
+static uint8_t fat_read_header(struct fat_fs_struct* fs);
+static cluster_t fat_get_next_cluster(const struct fat_fs_struct* fs, cluster_t cluster_num);
+static offset_t fat_cluster_offset(const struct fat_fs_struct* fs, cluster_t cluster_num);
+static uint8_t fat_dir_entry_read_callback(uint8_t* buffer, offset_t offset, void* p);
+#if FAT_LFN_SUPPORT
+static uint8_t fat_calc_83_checksum(const uint8_t* file_name_83);
+#endif
+static uint8_t fat_get_fs_free_16_callback(uint8_t* buffer, offset_t offset, void* p);
+#if FAT_FAT32_SUPPORT
+static uint8_t fat_get_fs_free_32_callback(uint8_t* buffer, offset_t offset, void* p);
+#endif
+#if FAT_WRITE_SUPPORT
+static cluster_t fat_append_clusters(struct fat_fs_struct* fs, cluster_t cluster_num, cluster_t count);
+static uint8_t fat_free_clusters(struct fat_fs_struct* fs, cluster_t cluster_num);
+static uint8_t fat_terminate_clusters(struct fat_fs_struct* fs, cluster_t cluster_num);
+static uint8_t fat_clear_cluster(const struct fat_fs_struct* fs, cluster_t cluster_num);
+static uintptr_t fat_clear_cluster_callback(uint8_t* buffer, offset_t offset, void* p);
+static offset_t fat_find_offset_for_dir_entry(struct fat_fs_struct* fs, const struct fat_dir_struct* parent, const struct fat_dir_entry_struct* dir_entry);
+static uint8_t fat_write_dir_entry(const struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry);
+#if FAT_DATETIME_SUPPORT
+static void fat_set_file_modification_date(struct fat_dir_entry_struct* dir_entry, uint16_t year, uint8_t month, uint8_t day);
+static void fat_set_file_modification_time(struct fat_dir_entry_struct* dir_entry, uint8_t hour, uint8_t min, uint8_t sec);
+#endif
+#endif
+/**
+* \ingroup fat_fs
+* Opens a FAT filesystem.
+*
+* \param[in] partition Discriptor of partition on which the filesystem resides.
+* \returns 0 on error, a FAT filesystem descriptor on success.
+* \see fat_close
+*/
+struct fat_fs_struct* fat_open(struct partition_struct* partition)
+{
+if(!partition ||
+#if FAT_WRITE_SUPPORT
+!partition->device_write ||
+!partition->device_write_interval
+#else
+0
+#endif
+)
+return 0;
+#if USE_DYNAMIC_MEMORY
+struct fat_fs_struct* fs = malloc(sizeof(*fs));
+if(!fs)
+return 0;
+#else
+struct fat_fs_struct* fs = fat_fs_handles;
+uint8_t i;
+for(i = 0; i < FAT_FS_COUNT; ++i)
+{
+if(!fs->partition)
+break;
+++fs;
+}
+if(i >= FAT_FS_COUNT)
+return 0;
+#endif
+memset(fs, 0, sizeof(*fs));
+fs->partition = partition;
+if(!fat_read_header(fs))
+{
+#if USE_DYNAMIC_MEMORY
+free(fs);
+#else
+fs->partition = 0;
+#endif
+return 0;
+}
+return fs;
+}
+/**
+* \ingroup fat_fs
+* Closes a FAT filesystem.
+*
+* When this function returns, the given filesystem descriptor
+* will be invalid.
+*
+* \param[in] fs The filesystem to close.
+* \see fat_open
+*/
+void fat_close(struct fat_fs_struct* fs)
+{
+if(!fs)
+return;
+#if USE_DYNAMIC_MEMORY
+free(fs);
+#else
+fs->partition = 0;
+#endif
+}
+/**
+* \ingroup fat_fs
+* Reads and parses the header of a FAT filesystem.
+*
+* \param[in,out] fs The filesystem for which to parse the header.
+* \returns 0 on failure, 1 on success.
+*/
+uint8_t fat_read_header(struct fat_fs_struct* fs)
+{
+if(!fs)
+return 0;
+struct partition_struct* partition = fs->partition;
+if(!partition)
+return 0;
+/* read fat parameters */
+#if FAT_FAT32_SUPPORT
+uint8_t buffer[37];
+#else
+uint8_t buffer[25];
+#endif
+offset_t partition_offset = (offset_t) partition->offset * 512;
+if(!partition->device_read(partition_offset + 0x0b, buffer, sizeof(buffer)))
+return 0;
+uint16_t bytes_per_sector = read16(&buffer[0x00]);
+uint16_t reserved_sectors = read16(&buffer[0x03]);
+uint8_t sectors_per_cluster = buffer[0x02];
+uint8_t fat_copies = buffer[0x05];
+uint16_t max_root_entries = read16(&buffer[0x06]);
+uint16_t sector_count_16 = read16(&buffer[0x08]);
+uint16_t sectors_per_fat = read16(&buffer[0x0b]);
+uint32_t sector_count = read32(&buffer[0x15]);
+#if FAT_FAT32_SUPPORT
+uint32_t sectors_per_fat32 = read32(&buffer[0x19]);
+uint32_t cluster_root_dir = read32(&buffer[0x21]);
+#endif
+if(sector_count == 0)
+{
+if(sector_count_16 == 0)
+/* illegal volume size */
+return 0;
+else
+sector_count = sector_count_16;
+}
+#if FAT_FAT32_SUPPORT
+if(sectors_per_fat != 0)
+sectors_per_fat32 = sectors_per_fat;
+else if(sectors_per_fat32 == 0)
+/* this is neither FAT16 nor FAT32 */
+return 0;
+#else
+if(sectors_per_fat == 0)
+/* this is not a FAT16 */
+return 0;
+#endif
+/* determine the type of FAT we have here */
+uint32_t data_sector_count = sector_count
+- reserved_sectors
+#if FAT_FAT32_SUPPORT
+- sectors_per_fat32 * fat_copies
+#else
+- (uint32_t) sectors_per_fat * fat_copies
+#endif
+- ((max_root_entries * 32 + bytes_per_sector - 1) / bytes_per_sector);
+uint32_t data_cluster_count = data_sector_count / sectors_per_cluster;
+if(data_cluster_count < 4085)
+/* this is a FAT12, not supported */
+return 0;
+else if(data_cluster_count < 65525)
+/* this is a FAT16 */
+partition->type = PARTITION_TYPE_FAT16;
+else
+/* this is a FAT32 */
+partition->type = PARTITION_TYPE_FAT32;
+/* fill header information */
+struct fat_header_struct* header = &fs->header;
+memset(header, 0, sizeof(*header));
+header->size = (offset_t) sector_count * bytes_per_sector;
+header->fat_offset = /* jump to partition */
+partition_offset +
+/* jump to fat */
+(offset_t) reserved_sectors * bytes_per_sector;
+header->fat_size = (data_cluster_count + 2) * (partition->type == PARTITION_TYPE_FAT16 ? 2 : 4);
+header->sector_size = bytes_per_sector;
+header->cluster_size = (uint16_t) bytes_per_sector * sectors_per_cluster;
+#if FAT_FAT32_SUPPORT
+if(partition->type == PARTITION_TYPE_FAT16)
+#endif
+{
+header->root_dir_offset = /* jump to fats */
+header->fat_offset +
+/* jump to root directory entries */
+(offset_t) fat_copies * sectors_per_fat * bytes_per_sector;
+header->cluster_zero_offset = /* jump to root directory entries */
+header->root_dir_offset +
+/* skip root directory entries */
+(offset_t) max_root_entries * 32;
+}
+#if FAT_FAT32_SUPPORT
+else
+{
+header->cluster_zero_offset = /* jump to fats */
+header->fat_offset +
+/* skip fats */
+(offset_t) fat_copies * sectors_per_fat32 * bytes_per_sector;
+header->root_dir_cluster = cluster_root_dir;
+}
+#endif
+return 1;
+}
+/**
+* \ingroup fat_fs
+* Retrieves the next following cluster of a given cluster.
+*
+* Using the filesystem file allocation table, this function returns
+* the number of the cluster containing the data directly following
+* the data within the cluster with the given number.
+*
+* \param[in] fs The filesystem for which to determine the next cluster.
+* \param[in] cluster_num The number of the cluster for which to determine its successor.
+* \returns The wanted cluster number, or 0 on error.
+*/
+cluster_t fat_get_next_cluster(const struct fat_fs_struct* fs, cluster_t cluster_num)
+{
+if(!fs || cluster_num < 2)
+return 0;
+#if FAT_FAT32_SUPPORT
+if(fs->partition->type == PARTITION_TYPE_FAT32)
+{
+/* read appropriate fat entry */
+uint32_t fat_entry;
+if(!fs->partition->device_read(fs->header.fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry)))
+return 0;
+/* determine next cluster from fat */
+cluster_num = ltoh32(fat_entry);
+if(cluster_num == FAT32_CLUSTER_FREE ||
+cluster_num == FAT32_CLUSTER_BAD ||
+(cluster_num >= FAT32_CLUSTER_RESERVED_MIN && cluster_num <= FAT32_CLUSTER_RESERVED_MAX) ||
+(cluster_num >= FAT32_CLUSTER_LAST_MIN && cluster_num <= FAT32_CLUSTER_LAST_MAX))
+return 0;
+}
+else
+#endif
+{
+/* read appropriate fat entry */
+uint16_t fat_entry;
+if(!fs->partition->device_read(fs->header.fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry)))
+return 0;
+/* determine next cluster from fat */
+cluster_num = ltoh16(fat_entry);
+if(cluster_num == FAT16_CLUSTER_FREE ||
+cluster_num == FAT16_CLUSTER_BAD ||
+(cluster_num >= FAT16_CLUSTER_RESERVED_MIN && cluster_num <= FAT16_CLUSTER_RESERVED_MAX) ||
+(cluster_num >= FAT16_CLUSTER_LAST_MIN && cluster_num <= FAT16_CLUSTER_LAST_MAX))
+return 0;
+}
+return cluster_num;
+}
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_fs
+* Appends a new cluster chain to an existing one.
+*
+* Set cluster_num to zero to create a completely new one.
+*
+* \param[in] fs The file system on which to operate.
+* \param[in] cluster_num The cluster to which to append the new chain.
+* \param[in] count The number of clusters to allocate.
+* \returns 0 on failure, the number of the first new cluster on success.
+*/
+cluster_t fat_append_clusters(struct fat_fs_struct* fs, cluster_t cluster_num, cluster_t count)
+{
+if(!fs)
+return 0;
+device_read_t device_read = fs->partition->device_read;
+device_write_t device_write = fs->partition->device_write;
+offset_t fat_offset = fs->header.fat_offset;
+cluster_t count_left = count;
+cluster_t cluster_current = fs->cluster_free;
+cluster_t cluster_next = 0;
+cluster_t cluster_count;
+uint16_t fat_entry16;
+#if FAT_FAT32_SUPPORT
+uint32_t fat_entry32;
+uint8_t is_fat32 = (fs->partition->type == PARTITION_TYPE_FAT32);
+if(is_fat32)
+cluster_count = fs->header.fat_size / sizeof(fat_entry32);
+else
+#endif
+cluster_count = fs->header.fat_size / sizeof(fat_entry16);
+fs->cluster_free = 0;
+for(cluster_t cluster_left = cluster_count; cluster_left > 0; --cluster_left, ++cluster_current)
+{
+if(cluster_current < 2 || cluster_current >= cluster_count)
+cluster_current = 2;
+#if FAT_FAT32_SUPPORT
+if(is_fat32)
+{
+if(!device_read(fat_offset + (offset_t) cluster_current * sizeof(fat_entry32), (uint8_t*) &fat_entry32, sizeof(fat_entry32)))
+return 0;
+}
+else
+#endif
+{
+if(!device_read(fat_offset + (offset_t) cluster_current * sizeof(fat_entry16), (uint8_t*) &fat_entry16, sizeof(fat_entry16)))
+return 0;
+}
+#if FAT_FAT32_SUPPORT
+if(is_fat32)
+{
+/* check if this is a free cluster */
+if(fat_entry32 != HTOL32(FAT32_CLUSTER_FREE))
+continue;
+/* If we don't need this free cluster for the
+* current allocation, we keep it in mind for
+* the next time.
+*/
+if(count_left == 0)
+{
+fs->cluster_free = cluster_current;
+break;
+}
+/* allocate cluster */
+if(cluster_next == 0)
+fat_entry32 = HTOL32(FAT32_CLUSTER_LAST_MAX);
+else
+fat_entry32 = htol32(cluster_next);
+if(!device_write(fat_offset + (offset_t) cluster_current * sizeof(fat_entry32), (uint8_t*) &fat_entry32, sizeof(fat_entry32)))
+break;
+}
+else
+#endif
+{
+/* check if this is a free cluster */
+if(fat_entry16 != HTOL16(FAT16_CLUSTER_FREE))
+continue;
+/* If we don't need this free cluster for the
+* current allocation, we keep it in mind for
+* the next time.
+*/
+if(count_left == 0)
+{
+fs->cluster_free = cluster_current;
+break;
+}
+/* allocate cluster */
+if(cluster_next == 0)
+fat_entry16 = HTOL16(FAT16_CLUSTER_LAST_MAX);
+else
+fat_entry16 = htol16((uint16_t) cluster_next);
+if(!device_write(fat_offset + (offset_t) cluster_current * sizeof(fat_entry16), (uint8_t*) &fat_entry16, sizeof(fat_entry16)))
+break;
+}
+cluster_next = cluster_current;
+--count_left;
+}
+do
+{
+if(count_left > 0)
+break;
+/* We allocated a new cluster chain. Now join
+* it with the existing one (if any).
+*/
+if(cluster_num >= 2)
+{
+#if FAT_FAT32_SUPPORT
+if(is_fat32)
+{
+fat_entry32 = htol32(cluster_next);
+if(!device_write(fat_offset + (offset_t) cluster_num * sizeof(fat_entry32), (uint8_t*) &fat_entry32, sizeof(fat_entry32)))
+break;
+}
+else
+#endif
+{
+fat_entry16 = htol16((uint16_t) cluster_next);
+if(!device_write(fat_offset + (offset_t) cluster_num * sizeof(fat_entry16), (uint8_t*) &fat_entry16, sizeof(fat_entry16)))
+break;
+}
+}
+return cluster_next;
+} while(0);
+/* No space left on device or writing error.
+* Free up all clusters already allocated.
+*/
+fat_free_clusters(fs, cluster_next);
+return 0;
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_fs
+* Frees a cluster chain, or a part thereof.
+*
+* Marks the specified cluster and all clusters which are sequentially
+* referenced by it as free. They may then be used again for future
+* file allocations.
+*
+* \note If this function is used for freeing just a part of a cluster
+*       chain, the new end of the chain is not correctly terminated
+*       within the FAT. Use fat_terminate_clusters() instead.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in] cluster_num The starting cluster of the chain which to free.
+* \returns 0 on failure, 1 on success.
+* \see fat_terminate_clusters
+*/
+uint8_t fat_free_clusters(struct fat_fs_struct* fs, cluster_t cluster_num)
+{
+if(!fs || cluster_num < 2)
+return 0;
+offset_t fat_offset = fs->header.fat_offset;
+#if FAT_FAT32_SUPPORT
+if(fs->partition->type == PARTITION_TYPE_FAT32)
+{
+uint32_t fat_entry;
+while(cluster_num)
+{
+if(!fs->partition->device_read(fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry)))
+return 0;
+/* get next cluster of current cluster before freeing current cluster */
+uint32_t cluster_num_next = ltoh32(fat_entry);
+if(cluster_num_next == FAT32_CLUSTER_FREE)
+return 1;
+if(cluster_num_next == FAT32_CLUSTER_BAD ||
+(cluster_num_next >= FAT32_CLUSTER_RESERVED_MIN &&
+cluster_num_next <= FAT32_CLUSTER_RESERVED_MAX
+)
+)
+return 0;
+if(cluster_num_next >= FAT32_CLUSTER_LAST_MIN && cluster_num_next <= FAT32_CLUSTER_LAST_MAX)
+cluster_num_next = 0;
+/* We know we will free the cluster, so remember it as
+* free for the next allocation.
+*/
+if(!fs->cluster_free)
+fs->cluster_free = cluster_num;
+/* free cluster */
+fat_entry = HTOL32(FAT32_CLUSTER_FREE);
+fs->partition->device_write(fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry));
+/* We continue in any case here, even if freeing the cluster failed.
+* The cluster is lost, but maybe we can still free up some later ones.
+*/
+cluster_num = cluster_num_next;
+}
+}
+else
+#endif
+{
+uint16_t fat_entry;
+while(cluster_num)
+{
+if(!fs->partition->device_read(fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry)))
+return 0;
+/* get next cluster of current cluster before freeing current cluster */
+uint16_t cluster_num_next = ltoh16(fat_entry);
+if(cluster_num_next == FAT16_CLUSTER_FREE)
+return 1;
+if(cluster_num_next == FAT16_CLUSTER_BAD ||
+(cluster_num_next >= FAT16_CLUSTER_RESERVED_MIN &&
+cluster_num_next <= FAT16_CLUSTER_RESERVED_MAX
+)
+)
+return 0;
+if(cluster_num_next >= FAT16_CLUSTER_LAST_MIN && cluster_num_next <= FAT16_CLUSTER_LAST_MAX)
+cluster_num_next = 0;
+/* free cluster */
+fat_entry = HTOL16(FAT16_CLUSTER_FREE);
+fs->partition->device_write(fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry));
+/* We continue in any case here, even if freeing the cluster failed.
+* The cluster is lost, but maybe we can still free up some later ones.
+*/
+cluster_num = cluster_num_next;
+}
+}
+return 1;
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_fs
+* Frees a part of a cluster chain and correctly terminates the rest.
+*
+* Marks the specified cluster as the new end of a cluster chain and
+* frees all following clusters.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in] cluster_num The new end of the cluster chain.
+* \returns 0 on failure, 1 on success.
+* \see fat_free_clusters
+*/
+uint8_t fat_terminate_clusters(struct fat_fs_struct* fs, cluster_t cluster_num)
+{
+if(!fs || cluster_num < 2)
+return 0;
+/* fetch next cluster before overwriting the cluster entry */
+cluster_t cluster_num_next = fat_get_next_cluster(fs, cluster_num);
+/* mark cluster as the last one */
+#if FAT_FAT32_SUPPORT
+if(fs->partition->type == PARTITION_TYPE_FAT32)
+{
+uint32_t fat_entry = HTOL32(FAT32_CLUSTER_LAST_MAX);
+if(!fs->partition->device_write(fs->header.fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry)))
+return 0;
+}
+else
+#endif
+{
+uint16_t fat_entry = HTOL16(FAT16_CLUSTER_LAST_MAX);
+if(!fs->partition->device_write(fs->header.fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry)))
+return 0;
+}
+/* free remaining clusters */
+if(cluster_num_next)
+return fat_free_clusters(fs, cluster_num_next);
+else
+return 1;
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_fs
+* Clears a single cluster.
+*
+* The complete cluster is filled with zeros.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in] cluster_num The cluster to clear.
+* \returns 0 on failure, 1 on success.
+*/
+uint8_t fat_clear_cluster(const struct fat_fs_struct* fs, cluster_t cluster_num)
+{
+if(cluster_num < 2)
+return 0;
+offset_t cluster_offset = fat_cluster_offset(fs, cluster_num);
+uint8_t zero[16];
+memset(zero, 0, sizeof(zero));
+return fs->partition->device_write_interval(cluster_offset,
+zero,
+fs->header.cluster_size,
+fat_clear_cluster_callback,
+0
+);
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_fs
+* Callback function for clearing a cluster.
+*/
+uintptr_t fat_clear_cluster_callback(uint8_t* buffer, offset_t offset, void* p)
+{
+return 16;
+}
+#endif
+/**
+* \ingroup fat_fs
+* Calculates the offset of the specified cluster.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in] cluster_num The cluster whose offset to calculate.
+* \returns The cluster offset.
+*/
+offset_t fat_cluster_offset(const struct fat_fs_struct* fs, cluster_t cluster_num)
+{
+if(!fs || cluster_num < 2)
+return 0;
+return fs->header.cluster_zero_offset + (offset_t) (cluster_num - 2) * fs->header.cluster_size;
+}
+/**
+* \ingroup fat_file
+* Retrieves the directory entry of a path.
+*
+* The given path may both describe a file or a directory.
+*
+* \param[in] fs The FAT filesystem on which to search.
+* \param[in] path The path of which to read the directory entry.
+* \param[out] dir_entry The directory entry to fill.
+* \returns 0 on failure, 1 on success.
+* \see fat_read_dir
+*/
+uint8_t fat_get_dir_entry_of_path(struct fat_fs_struct* fs, const char* path, struct fat_dir_entry_struct* dir_entry)
+{
+if(!fs || !path || path[0] == '\0' || !dir_entry)
+return 0;
+if(path[0] == '/')
+++path;
+/* begin with the root directory */
+memset(dir_entry, 0, sizeof(*dir_entry));
+dir_entry->attributes = FAT_ATTRIB_DIR;
+while(1)
+{
+if(path[0] == '\0')
+return 1;
+struct fat_dir_struct* dd = fat_open_dir(fs, dir_entry);
+if(!dd)
+break;
+/* extract the next hierarchy we will search for */
+const char* sub_path = strchr(path, '/');
+uint8_t length_to_sep;
+if(sub_path)
+{
+length_to_sep = sub_path - path;
+++sub_path;
+}
+else
+{
+length_to_sep = strlen(path);
+sub_path = path + length_to_sep;
+}
+/* read directory entries */
+while(fat_read_dir(dd, dir_entry))
+{
+/* check if we have found the next hierarchy */
+if((strlen(dir_entry->long_name) != length_to_sep ||
+strncmp(path, dir_entry->long_name, length_to_sep) != 0))
+continue;
+fat_close_dir(dd);
+dd = 0;
+if(path[length_to_sep] == '\0')
+/* we iterated through the whole path and have found the file */
+return 1;
+if(dir_entry->attributes & FAT_ATTRIB_DIR)
+{
+/* we found a parent directory of the file we are searching for */
+path = sub_path;
+break;
+}
+/* a parent of the file exists, but not the file itself */
+return 0;
+}
+fat_close_dir(dd);
+}
+return 0;
+}
+/**
+* \ingroup fat_file
+* Opens a file on a FAT filesystem.
+*
+* \param[in] fs The filesystem on which the file to open lies.
+* \param[in] dir_entry The directory entry of the file to open.
+* \returns The file handle, or 0 on failure.
+* \see fat_close_file
+*/
+struct fat_file_struct* fat_open_file(struct fat_fs_struct* fs, const struct fat_dir_entry_struct* dir_entry)
+{
+if(!fs || !dir_entry || (dir_entry->attributes & FAT_ATTRIB_DIR))
+return 0;
+#if USE_DYNAMIC_MEMORY
+struct fat_file_struct* fd = malloc(sizeof(*fd));
+if(!fd)
+return 0;
+#else
+struct fat_file_struct* fd = fat_file_handles;
+uint8_t i;
+for(i = 0; i < FAT_FILE_COUNT; ++i)
+{
+if(!fd->fs)
+break;
+++fd;
+}
+if(i >= FAT_FILE_COUNT)
+return 0;
+#endif
+memcpy(&fd->dir_entry, dir_entry, sizeof(*dir_entry));
+fd->fs = fs;
+fd->pos = 0;
+fd->pos_cluster = dir_entry->cluster;
+return fd;
+}
+/**
+* \ingroup fat_file
+* Closes a file.
+*
+* \param[in] fd The file handle of the file to close.
+* \see fat_open_file
+*/
+void fat_close_file(struct fat_file_struct* fd)
+{
+if(fd)
+{
+#if FAT_DELAY_DIRENTRY_UPDATE
+/* write directory entry */
+fat_write_dir_entry(fd->fs, &fd->dir_entry);
+#endif
+#if USE_DYNAMIC_MEMORY
+free(fd);
+#else
+fd->fs = 0;
+#endif
+}
+}
+/**
+* \ingroup fat_file
+* Reads data from a file.
+*
+* The data requested is read from the current file location.
+*
+* \param[in] fd The file handle of the file from which to read.
+* \param[out] buffer The buffer into which to write.
+* \param[in] buffer_len The amount of data to read.
+* \returns The number of bytes read, 0 on end of file, or -1 on failure.
+* \see fat_write_file
+*/
+intptr_t fat_read_file(struct fat_file_struct* fd, uint8_t* buffer, uintptr_t buffer_len)
+{
+/* check arguments */
+if(!fd || !buffer || buffer_len < 1)
+return -1;
+/* determine number of bytes to read */
+if(fd->pos + buffer_len > fd->dir_entry.file_size)
+buffer_len = fd->dir_entry.file_size - fd->pos;
+if(buffer_len == 0)
+return 0;
+uint16_t cluster_size = fd->fs->header.cluster_size;
+cluster_t cluster_num = fd->pos_cluster;
+uintptr_t buffer_left = buffer_len;
+uint16_t first_cluster_offset = (uint16_t) (fd->pos & (cluster_size - 1));
+/* find cluster in which to start reading */
+if(!cluster_num)
+{
+cluster_num = fd->dir_entry.cluster;
+if(!cluster_num)
+{
+if(!fd->pos)
+return 0;
+else
+return -1;
+}
+if(fd->pos)
+{
+uint32_t pos = fd->pos;
+while(pos >= cluster_size)
+{
+pos -= cluster_size;
+cluster_num = fat_get_next_cluster(fd->fs, cluster_num);
+if(!cluster_num)
+return -1;
+}
+}
+}
+/* read data */
+do
+{
+/* calculate data size to copy from cluster */
+offset_t cluster_offset = fat_cluster_offset(fd->fs, cluster_num) + first_cluster_offset;
+uint16_t copy_length = cluster_size - first_cluster_offset;
+if(copy_length > buffer_left)
+copy_length = buffer_left;
+/* read data */
+if(!fd->fs->partition->device_read(cluster_offset, buffer, copy_length))
+return buffer_len - buffer_left;
+/* calculate new file position */
+buffer += copy_length;
+buffer_left -= copy_length;
+fd->pos += copy_length;
+if(first_cluster_offset + copy_length >= cluster_size)
+{
+/* we are on a cluster boundary, so get the next cluster */
+if((cluster_num = fat_get_next_cluster(fd->fs, cluster_num)))
+{
+first_cluster_offset = 0;
+}
+else
+{
+fd->pos_cluster = 0;
+return buffer_len - buffer_left;
+}
+}
+fd->pos_cluster = cluster_num;
+} while(buffer_left > 0); /* check if we are done */
+return buffer_len;
+}
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_file
+* Writes data to a file.
+*
+* The data is written to the current file location.
+*
+* \param[in] fd The file handle of the file to which to write.
+* \param[in] buffer The buffer from which to read the data to be written.
+* \param[in] buffer_len The amount of data to write.
+* \returns The number of bytes written (0 or something less than \c buffer_len on disk full) or -1 on failure.
+* \see fat_read_file
+*/
+intptr_t fat_write_file(struct fat_file_struct* fd, const uint8_t* buffer, uintptr_t buffer_len)
+{
+/* check arguments */
+if(!fd || !buffer || buffer_len < 1)
+return -1;
+if(fd->pos > fd->dir_entry.file_size)
+return -1;
+uint16_t cluster_size = fd->fs->header.cluster_size;
+cluster_t cluster_num = fd->pos_cluster;
+uintptr_t buffer_left = buffer_len;
+uint16_t first_cluster_offset = (uint16_t) (fd->pos & (cluster_size - 1));
+/* find cluster in which to start writing */
+if(!cluster_num)
+{
+cluster_num = fd->dir_entry.cluster;
+if(!cluster_num)
+{
+if(!fd->pos)
+{
+/* empty file */
+fd->dir_entry.cluster = cluster_num = fat_append_clusters(fd->fs, 0, 1);
+if(!cluster_num)
+return 0;
+}
+else
+{
+return -1;
+}
+}
+if(fd->pos)
+{
+uint32_t pos = fd->pos;
+cluster_t cluster_num_next;
+while(pos >= cluster_size)
+{
+pos -= cluster_size;
+cluster_num_next = fat_get_next_cluster(fd->fs, cluster_num);
+if(!cluster_num_next)
+{
+if(pos != 0)
+return -1; /* current file position points beyond end of file */
+/* the file exactly ends on a cluster boundary, and we append to it */
+cluster_num_next = fat_append_clusters(fd->fs, cluster_num, 1);
+if(!cluster_num_next)
+return 0;
+}
+cluster_num = cluster_num_next;
+}
+}
+}
+/* write data */
+do
+{
+/* calculate data size to write to cluster */
+offset_t cluster_offset = fat_cluster_offset(fd->fs, cluster_num) + first_cluster_offset;
+uint16_t write_length = cluster_size - first_cluster_offset;
+if(write_length > buffer_left)
+write_length = buffer_left;
+/* write data which fits into the current cluster */
+if(!fd->fs->partition->device_write(cluster_offset, buffer, write_length))
+break;
+/* calculate new file position */
+buffer += write_length;
+buffer_left -= write_length;
+fd->pos += write_length;
+if(first_cluster_offset + write_length >= cluster_size)
+{
+/* we are on a cluster boundary, so get the next cluster */
+cluster_t cluster_num_next = fat_get_next_cluster(fd->fs, cluster_num);
+if(!cluster_num_next && buffer_left > 0)
+/* we reached the last cluster, append a new one */
+cluster_num_next = fat_append_clusters(fd->fs, cluster_num, 1);
+if(!cluster_num_next)
+{
+fd->pos_cluster = 0;
+break;
+}
+cluster_num = cluster_num_next;
+first_cluster_offset = 0;
+}
+fd->pos_cluster = cluster_num;
+} while(buffer_left > 0); /* check if we are done */
+/* update directory entry */
+if(fd->pos > fd->dir_entry.file_size)
+{
+#if !FAT_DELAY_DIRENTRY_UPDATE
+uint32_t size_old = fd->dir_entry.file_size;
+#endif
+/* update file size */
+fd->dir_entry.file_size = fd->pos;
+#if !FAT_DELAY_DIRENTRY_UPDATE
+/* write directory entry */
+if(!fat_write_dir_entry(fd->fs, &fd->dir_entry))
+{
+/* We do not return an error here since we actually wrote
+* some data to disk. So we calculate the amount of data
+* we wrote to disk and which lies within the old file size.
+*/
+buffer_left = fd->pos - size_old;
+fd->pos = size_old;
+}
+#endif
+}
+return buffer_len - buffer_left;
+}
+#endif
+/**
+* \ingroup fat_file
+* Repositions the read/write file offset.
+*
+* Changes the file offset where the next call to fat_read_file()
+* or fat_write_file() starts reading/writing.
+*
+* If the new offset is beyond the end of the file, fat_resize_file()
+* is implicitly called, i.e. the file is expanded.
+*
+* The new offset can be given in different ways determined by
+* the \c whence parameter:
+* - \b FAT_SEEK_SET: \c *offset is relative to the beginning of the file.
+* - \b FAT_SEEK_CUR: \c *offset is relative to the current file position.
+* - \b FAT_SEEK_END: \c *offset is relative to the end of the file.
+*
+* The resulting absolute offset is written to the location the \c offset
+* parameter points to.
+*
+* Calling this function can also be used to retrieve the current file position:
+\code
+int32_t file_pos = 0;
+if(!fat_seek_file(fd, &file_pos, FAT_SEEK_CUR))
+{
+// error
+}
+// file_pos now contains the absolute file position
+\endcode
+*
+* \param[in] fd The file decriptor of the file on which to seek.
+* \param[in,out] offset A pointer to the new offset, as affected by the \c whence
+*                   parameter. The function writes the new absolute offset
+*                   to this location before it returns.
+* \param[in] whence Affects the way \c offset is interpreted, see above.
+* \returns 0 on failure, 1 on success.
+*/
+uint8_t fat_seek_file(struct fat_file_struct* fd, int32_t* offset, uint8_t whence)
+{
+if(!fd || !offset)
+return 0;
+uint32_t new_pos = fd->pos;
+switch(whence)
+{
+case FAT_SEEK_SET:
+new_pos = *offset;
+break;
+case FAT_SEEK_CUR:
+new_pos += *offset;
+break;
+case FAT_SEEK_END:
+new_pos = fd->dir_entry.file_size + *offset;
+break;
+default:
+return 0;
+}
+if(new_pos > fd->dir_entry.file_size
+#if FAT_WRITE_SUPPORT
+&& !fat_resize_file(fd, new_pos)
+#endif
+)
+return 0;
+fd->pos = new_pos;
+fd->pos_cluster = 0;
+*offset = (int32_t) new_pos;
+return 1;
+}
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_file
+* Resizes a file to have a specific size.
+*
+* Enlarges or shrinks the file pointed to by the file descriptor to have
+* exactly the specified size.
+*
+* If the file is truncated, all bytes having an equal or larger offset
+* than the given size are lost. If the file is expanded, the additional
+* bytes are allocated.
+*
+* \note Please be aware that this function just allocates or deallocates disk
+* space, it does not explicitely clear it. To avoid data leakage, this
+* must be done manually.
+*
+* \param[in] fd The file decriptor of the file which to resize.
+* \param[in] size The new size of the file.
+* \returns 0 on failure, 1 on success.
+*/
+uint8_t fat_resize_file(struct fat_file_struct* fd, uint32_t size)
+{
+if(!fd)
+return 0;
+cluster_t cluster_num = fd->dir_entry.cluster;
+uint16_t cluster_size = fd->fs->header.cluster_size;
+uint32_t size_new = size;
+do
+{
+if(cluster_num == 0 && size_new == 0)
+/* the file stays empty */
+break;
+/* seek to the next cluster as long as we need the space */
+while(size_new > cluster_size)
+{
+/* get next cluster of file */
+cluster_t cluster_num_next = fat_get_next_cluster(fd->fs, cluster_num);
+if(cluster_num_next)
+{
+cluster_num = cluster_num_next;
+size_new -= cluster_size;
+}
+else
+{
+break;
+}
+}
+if(size_new > cluster_size || cluster_num == 0)
+{
+/* Allocate new cluster chain and append
+* it to the existing one, if available.
+*/
+cluster_t cluster_count = (size_new + cluster_size - 1) / cluster_size;
+cluster_t cluster_new_chain = fat_append_clusters(fd->fs, cluster_num, cluster_count);
+if(!cluster_new_chain)
+return 0;
+if(!cluster_num)
+{
+cluster_num = cluster_new_chain;
+fd->dir_entry.cluster = cluster_num;
+}
+}
+/* write new directory entry */
+fd->dir_entry.file_size = size;
+if(size == 0)
+fd->dir_entry.cluster = 0;
+if(!fat_write_dir_entry(fd->fs, &fd->dir_entry))
+return 0;
+if(size == 0)
+{
+/* free all clusters of file */
+fat_free_clusters(fd->fs, cluster_num);
+}
+else if(size_new <= cluster_size)
+{
+/* free all clusters no longer needed */
+fat_terminate_clusters(fd->fs, cluster_num);
+}
+} while(0);
+/* correct file position */
+if(size < fd->pos)
+{
+fd->pos = size;
+fd->pos_cluster = 0;
+}
+return 1;
+}
+#endif
+/**
+* \ingroup fat_dir
+* Opens a directory.
+*
+* \param[in] fs The filesystem on which the directory to open resides.
+* \param[in] dir_entry The directory entry which stands for the directory to open.
+* \returns An opaque directory descriptor on success, 0 on failure.
+* \see fat_close_dir
+*/
+struct fat_dir_struct* fat_open_dir(struct fat_fs_struct* fs, const struct fat_dir_entry_struct* dir_entry)
+{
+if(!fs || !dir_entry || !(dir_entry->attributes & FAT_ATTRIB_DIR))
+return 0;
+#if USE_DYNAMIC_MEMORY
+struct fat_dir_struct* dd = malloc(sizeof(*dd));
+if(!dd)
+return 0;
+#else
+struct fat_dir_struct* dd = fat_dir_handles;
+uint8_t i;
+for(i = 0; i < FAT_DIR_COUNT; ++i)
+{
+if(!dd->fs)
+break;
+++dd;
+}
+if(i >= FAT_DIR_COUNT)
+return 0;
+#endif
+memcpy(&dd->dir_entry, dir_entry, sizeof(*dir_entry));
+dd->fs = fs;
+dd->entry_cluster = dir_entry->cluster;
+dd->entry_offset = 0;
+return dd;
+}
+/**
+* \ingroup fat_dir
+* Closes a directory descriptor.
+*
+* This function destroys a directory descriptor which was
+* previously obtained by calling fat_open_dir(). When this
+* function returns, the given descriptor will be invalid.
+*
+* \param[in] dd The directory descriptor to close.
+* \see fat_open_dir
+*/
+void fat_close_dir(struct fat_dir_struct* dd)
+{
+if(dd)
+#if USE_DYNAMIC_MEMORY
+free(dd);
+#else
+dd->fs = 0;
+#endif
+}
+/**
+* \ingroup fat_dir
+* Reads the next directory entry contained within a parent directory.
+*
+* \param[in] dd The descriptor of the parent directory from which to read the entry.
+* \param[out] dir_entry Pointer to a buffer into which to write the directory entry information.
+* \returns 0 on failure, 1 on success.
+* \see fat_reset_dir
+*/
+uint8_t fat_read_dir(struct fat_dir_struct* dd, struct fat_dir_entry_struct* dir_entry)
+{
+if(!dd || !dir_entry)
+return 0;
+/* get current position of directory handle */
+struct fat_fs_struct* fs = dd->fs;
+const struct fat_header_struct* header = &fs->header;
+uint16_t cluster_size = header->cluster_size;
+cluster_t cluster_num = dd->entry_cluster;
+uint16_t cluster_offset = dd->entry_offset;
+struct fat_read_dir_callback_arg arg;
+if(cluster_offset >= cluster_size)
+{
+/* The latest call hit the border of the last cluster in
+* the chain, but it still returned a directory entry.
+* So we now reset the handle and signal the caller the
+* end of the listing.
+*/
+fat_reset_dir(dd);
+return 0;
+}
+/* reset callback arguments */
+memset(&arg, 0, sizeof(arg));
+memset(dir_entry, 0, sizeof(*dir_entry));
+arg.dir_entry = dir_entry;
+/* check if we read from the root directory */
+if(cluster_num == 0)
+{
+#if FAT_FAT32_SUPPORT
+if(fs->partition->type == PARTITION_TYPE_FAT32)
+cluster_num = header->root_dir_cluster;
+else
+#endif
+cluster_size = header->cluster_zero_offset - header->root_dir_offset;
+}
+/* read entries */
+uint8_t buffer[32];
+while(!arg.finished)
+{
+/* read directory entries up to the cluster border */
+uint16_t cluster_left = cluster_size - cluster_offset;
+offset_t pos = cluster_offset;
+if(cluster_num == 0)
+pos += header->root_dir_offset;
+else
+pos += fat_cluster_offset(fs, cluster_num);
+arg.bytes_read = 0;
+if(!fs->partition->device_read_interval(pos,
+buffer,
+sizeof(buffer),
+cluster_left,
+fat_dir_entry_read_callback,
+&arg)
+)
+return 0;
+cluster_offset += arg.bytes_read;
+if(cluster_offset >= cluster_size)
+{
+/* we reached the cluster border and switch to the next cluster */
+/* get number of next cluster */
+if((cluster_num = fat_get_next_cluster(fs, cluster_num)) != 0)
+{
+cluster_offset = 0;
+continue;
+}
+/* we are at the end of the cluster chain */
+if(!arg.finished)
+{
+/* directory entry not found, reset directory handle */
+fat_reset_dir(dd);
+return 0;
+}
+else
+{
+/* The current execution of the function has been successful,
+* so we can not signal an end of the directory listing to
+* the caller, but must wait for the next call. So we keep an
+* invalid cluster offset to mark this directory handle's
+* traversal as finished.
+*/
+}
+break;
+}
+}
+dd->entry_cluster = cluster_num;
+dd->entry_offset = cluster_offset;
+return arg.finished;
+}
+/**
+* \ingroup fat_dir
+* Resets a directory handle.
+*
+* Resets the directory handle such that reading restarts
+* with the first directory entry.
+*
+* \param[in] dd The directory handle to reset.
+* \returns 0 on failure, 1 on success.
+* \see fat_read_dir
+*/
+uint8_t fat_reset_dir(struct fat_dir_struct* dd)
+{
+if(!dd)
+return 0;
+dd->entry_cluster = dd->dir_entry.cluster;
+dd->entry_offset = 0;
+return 1;
+}
+/**
+* \ingroup fat_fs
+* Callback function for reading a directory entry.
+*
+* Interprets a raw directory entry and puts the contained
+* information into a fat_dir_entry_struct structure.
+*
+* For a single file there may exist multiple directory
+* entries. All except the last one are lfn entries, which
+* contain parts of the long filename. The last directory
+* entry is a traditional 8.3 style one. It contains all
+* other information like size, cluster, date and time.
+*
+* \param[in] buffer A pointer to 32 bytes of raw data.
+* \param[in] offset The absolute offset of the raw data.
+* \param[in,out] p An argument structure controlling operation.
+* \returns 0 on failure or completion, 1 if reading has
+*          to be continued
+*/
+uint8_t fat_dir_entry_read_callback(uint8_t* buffer, offset_t offset, void* p)
+{
+struct fat_read_dir_callback_arg* arg = p;
+struct fat_dir_entry_struct* dir_entry = arg->dir_entry;
+arg->bytes_read += 32;
+/* skip deleted or empty entries */
+if(buffer[0] == FAT_DIRENTRY_DELETED || !buffer[0])
+{
+#if FAT_LFN_SUPPORT
+arg->checksum = 0;
+#endif
+return 1;
+}
+#if !FAT_LFN_SUPPORT
+/* skip lfn entries */
+if(buffer[11] == 0x0f)
+return 1;
+#endif
+char* long_name = dir_entry->long_name;
+#if FAT_LFN_SUPPORT
+if(buffer[11] == 0x0f)
+{
+/* checksum validation */
+if(arg->checksum == 0 || arg->checksum != buffer[13])
+{
+/* reset directory entry */
+memset(dir_entry, 0, sizeof(*dir_entry));
+arg->checksum = buffer[13];
+dir_entry->entry_offset = offset;
+}
+/* lfn supports unicode, but we do not, for now.
+* So we assume pure ascii and read only every
+* second byte.
+*/
+uint16_t char_offset = ((buffer[0] & 0x3f) - 1) * 13;
+const uint8_t char_mapping[] = { 1, 3, 5, 7, 9, 14, 16, 18, 20, 22, 24, 28, 30 };
+for(uint8_t i = 0; i <= 12 && char_offset + i < sizeof(dir_entry->long_name) - 1; ++i)
+long_name[char_offset + i] = buffer[char_mapping[i]];
+return 1;
+}
+else
+#endif
+{
+#if FAT_LFN_SUPPORT
+/* if we do not have a long name or the previous lfn does not match, take the 8.3 name */
+if(long_name[0] == '\0' || arg->checksum != fat_calc_83_checksum(buffer))
+#endif
+{
+/* reset directory entry */
+memset(dir_entry, 0, sizeof(*dir_entry));
+dir_entry->entry_offset = offset;
+uint8_t i;
+for(i = 0; i < 8; ++i)
+{
+if(buffer[i] == ' ')
+break;
+long_name[i] = buffer[i];
+/* Windows NT and later versions do not store lfn entries
+* for 8.3 names which have a lowercase basename, extension
+* or both when everything else is uppercase. They use two
+* extra bits to signal a lowercase basename or extension.
+*/
+if((buffer[12] & 0x08) && buffer[i] >= 'A' && buffer[i] <= 'Z')
+long_name[i] += 'a' - 'A';
+}
+if(long_name[0] == 0x05)
+long_name[0] = (char) FAT_DIRENTRY_DELETED;
+if(buffer[8] != ' ')
+{
+long_name[i++] = '.';
+uint8_t j = 8;
+for(; j < 11; ++j)
+{
+if(buffer[j] == ' ')
+break;
+long_name[i] = buffer[j];
+/* See above for the lowercase 8.3 name handling of
+* Windows NT and later.
+*/
+if((buffer[12] & 0x10) && buffer[j] >= 'A' && buffer[j] <= 'Z')
+long_name[i] += 'a' - 'A';
+++i;
+}
+}
+long_name[i] = '\0';
+}
+/* extract properties of file and store them within the structure */
+dir_entry->attributes = buffer[11];
+dir_entry->cluster = read16(&buffer[26]);
+#if FAT_FAT32_SUPPORT
+dir_entry->cluster |= ((cluster_t) read16(&buffer[20])) << 16;
+#endif
+dir_entry->file_size = read32(&buffer[28]);
+#if FAT_DATETIME_SUPPORT
+dir_entry->modification_time = read16(&buffer[22]);
+dir_entry->modification_date = read16(&buffer[24]);
+#endif
+arg->finished = 1;
+return 0;
+}
+}
+#if DOXYGEN || FAT_LFN_SUPPORT
+/**
+* \ingroup fat_fs
+* Calculates the checksum for 8.3 names used within the
+* corresponding lfn directory entries.
+*
+* \param[in] file_name_83 The 11-byte file name buffer.
+* \returns The checksum of the given file name.
+*/
+uint8_t fat_calc_83_checksum(const uint8_t* file_name_83)
+{
+uint8_t checksum = file_name_83[0];
+for(uint8_t i = 1; i < 11; ++i)
+checksum = ((checksum >> 1) | (checksum << 7)) + file_name_83[i];
+return checksum;
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_fs
+* Searches for space where to store a directory entry.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in] parent The directory in which to search.
+* \param[in] dir_entry The directory entry for which to search space.
+* \returns 0 on failure, a device offset on success.
+*/
+offset_t fat_find_offset_for_dir_entry(struct fat_fs_struct* fs, const struct fat_dir_struct* parent, const struct fat_dir_entry_struct* dir_entry)
+{
+if(!fs || !dir_entry)
+return 0;
+/* search for a place where to write the directory entry to disk */
+#if FAT_LFN_SUPPORT
+uint8_t free_dir_entries_needed = (strlen(dir_entry->long_name) + 12) / 13 + 1;
+uint8_t free_dir_entries_found = 0;
+#endif
+cluster_t cluster_num = parent->dir_entry.cluster;
+offset_t dir_entry_offset = 0;
+offset_t offset = 0;
+offset_t offset_to = 0;
+#if FAT_FAT32_SUPPORT
+uint8_t is_fat32 = (fs->partition->type == PARTITION_TYPE_FAT32);
+#endif
+if(cluster_num == 0)
+{
+#if FAT_FAT32_SUPPORT
+if(is_fat32)
+{
+cluster_num = fs->header.root_dir_cluster;
+}
+else
+#endif
+{
+/* we read/write from the root directory entry */
+offset = fs->header.root_dir_offset;
+offset_to = fs->header.cluster_zero_offset;
+dir_entry_offset = offset;
+}
+}
+while(1)
+{
+if(offset == offset_to)
+{
+if(cluster_num == 0)
+/* We iterated through the whole root directory and
+* could not find enough space for the directory entry.
+*/
+return 0;
+if(offset)
+{
+/* We reached a cluster boundary and have to
+* switch to the next cluster.
+*/
+cluster_t cluster_next = fat_get_next_cluster(fs, cluster_num);
+if(!cluster_next)
+{
+cluster_next = fat_append_clusters(fs, cluster_num, 1);
+if(!cluster_next)
+return 0;
+/* we appended a new cluster and know it is free */
+dir_entry_offset = fs->header.cluster_zero_offset +
+(offset_t) (cluster_next - 2) * fs->header.cluster_size;
+/* clear cluster to avoid garbage directory entries */
+fat_clear_cluster(fs, cluster_next);
+break;
+}
+cluster_num = cluster_next;
+}
+offset = fat_cluster_offset(fs, cluster_num);
+offset_to = offset + fs->header.cluster_size;
+dir_entry_offset = offset;
+#if FAT_LFN_SUPPORT
+free_dir_entries_found = 0;
+#endif
+}
+/* read next lfn or 8.3 entry */
+uint8_t first_char;
+if(!fs->partition->device_read(offset, &first_char, sizeof(first_char)))
+return 0;
+/* check if we found a free directory entry */
+if(first_char == FAT_DIRENTRY_DELETED || !first_char)
+{
+/* check if we have the needed number of available entries */
+#if FAT_LFN_SUPPORT
+++free_dir_entries_found;
+if(free_dir_entries_found >= free_dir_entries_needed)
+#endif
+break;
+offset += 32;
+}
+else
+{
+offset += 32;
+dir_entry_offset = offset;
+#if FAT_LFN_SUPPORT
+free_dir_entries_found = 0;
+#endif
+}
+}
+return dir_entry_offset;
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_fs
+* Writes a directory entry to disk.
+*
+* \note The file name is not checked for invalid characters.
+*
+* \note The generation of the short 8.3 file name is quite
+* simple. The first eight characters are used for the filename.
+* The extension, if any, is made up of the first three characters
+* following the last dot within the long filename. If the
+* filename (without the extension) is longer than eight characters,
+* the lower byte of the cluster number replaces the last two
+* characters to avoid name clashes. In any other case, it is your
+* responsibility to avoid name clashes.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in] dir_entry The directory entry to write.
+* \returns 0 on failure, 1 on success.
+*/
+uint8_t fat_write_dir_entry(const struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry)
+{
+if(!fs || !dir_entry)
+return 0;
+#if FAT_DATETIME_SUPPORT
+{
+uint16_t year;
+uint8_t month;
+uint8_t day;
+uint8_t hour;
+uint8_t min;
+uint8_t sec;
+fat_get_datetime(&year, &month, &day, &hour, &min, &sec);
+fat_set_file_modification_date(dir_entry, year, month, day);
+fat_set_file_modification_time(dir_entry, hour, min, sec);
+}
+#endif
+device_write_t device_write = fs->partition->device_write;
+offset_t offset = dir_entry->entry_offset;
+const char* name = dir_entry->long_name;
+uint8_t name_len = strlen(name);
+#if FAT_LFN_SUPPORT
+uint8_t lfn_entry_count = (name_len + 12) / 13;
+#endif
+uint8_t buffer[32];
+/* write 8.3 entry */
+/* generate 8.3 file name */
+memset(&buffer[0], ' ', 11);
+char* name_ext = strrchr(name, '.');
+if(name_ext && *++name_ext)
+{
+uint8_t name_ext_len = strlen(name_ext);
+name_len -= name_ext_len + 1;
+if(name_ext_len > 3)
+#if FAT_LFN_SUPPORT
+name_ext_len = 3;
+#else
+return 0;
+#endif
+memcpy(&buffer[8], name_ext, name_ext_len);
+}
+if(name_len <= 8)
+{
+memcpy(buffer, name, name_len);
+#if FAT_LFN_SUPPORT
+/* For now, we create lfn entries for all files,
+* except the "." and ".." directory references.
+* This is to avoid difficulties with capitalization,
+* as 8.3 filenames allow uppercase letters only.
+*
+* Theoretically it would be possible to leave
+* the 8.3 entry alone if the basename and the
+* extension have no mixed capitalization.
+*/
+if(name[0] == '.' &&
+((name[1] == '.' && name[2] == '\0') ||
+name[1] == '\0')
+)
+lfn_entry_count = 0;
+#endif
+}
+else
+{
+#if FAT_LFN_SUPPORT
+memcpy(buffer, name, 8);
+/* Minimize 8.3 name clashes by appending
+* the lower byte of the cluster number.
+*/
+uint8_t num = dir_entry->cluster & 0xff;
+buffer[6] = (num < 0xa0) ? ('0' + (num >> 4)) : ('a' + (num >> 4));
+num &= 0x0f;
+buffer[7] = (num < 0x0a) ? ('0' + num) : ('a' + num);
+#else
+return 0;
+#endif
+}
+if(buffer[0] == FAT_DIRENTRY_DELETED)
+buffer[0] = 0x05;
+/* fill directory entry buffer */
+memset(&buffer[11], 0, sizeof(buffer) - 11);
+buffer[0x0b] = dir_entry->attributes;
+#if FAT_DATETIME_SUPPORT
+write16(&buffer[0x16], dir_entry->modification_time);
+write16(&buffer[0x18], dir_entry->modification_date);
+#endif
+#if FAT_FAT32_SUPPORT
+write16(&buffer[0x14], (uint16_t) (dir_entry->cluster >> 16));
+#endif
+write16(&buffer[0x1a], dir_entry->cluster);
+write32(&buffer[0x1c], dir_entry->file_size);
+/* write to disk */
+#if FAT_LFN_SUPPORT
+if(!device_write(offset + (uint16_t) lfn_entry_count * 32, buffer, sizeof(buffer)))
+#else
+if(!device_write(offset, buffer, sizeof(buffer)))
+#endif
+return 0;
+#if FAT_LFN_SUPPORT
+/* calculate checksum of 8.3 name */
+uint8_t checksum = fat_calc_83_checksum(buffer);
+/* write lfn entries */
+for(uint8_t lfn_entry = lfn_entry_count; lfn_entry > 0; --lfn_entry)
+{
+memset(buffer, 0xff, sizeof(buffer));
+/* set file name */
+const char* long_name_curr = name + (lfn_entry - 1) * 13;
+uint8_t i = 1;
+while(i < 0x1f)
+{
+buffer[i++] = *long_name_curr;
+buffer[i++] = 0;
+switch(i)
+{
+case 0x0b:
+i = 0x0e;
+break;
+case 0x1a:
+i = 0x1c;
+break;
+}
+if(!*long_name_curr++)
+break;
+}
+/* set index of lfn entry */
+buffer[0x00] = lfn_entry;
+if(lfn_entry == lfn_entry_count)
+buffer[0x00] |= FAT_DIRENTRY_LFNLAST;
+/* mark as lfn entry */
+buffer[0x0b] = 0x0f;
+/* set 8.3 checksum */
+buffer[0x0d] = checksum;
+/* clear reserved bytes */
+buffer[0x0c] = 0;
+buffer[0x1a] = 0;
+buffer[0x1b] = 0;
+/* write entry */
+device_write(offset, buffer, sizeof(buffer));
+offset += sizeof(buffer);
+}
+#endif
+return 1;
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_file
+* Creates a file.
+*
+* Creates a file and obtains the directory entry of the
+* new file. If the file to create already exists, the
+* directory entry of the existing file will be returned
+* within the dir_entry parameter.
+*
+* \note The file name is not checked for invalid characters.
+*
+* \note The generation of the short 8.3 file name is quite
+* simple. The first eight characters are used for the filename.
+* The extension, if any, is made up of the first three characters
+* following the last dot within the long filename. If the
+* filename (without the extension) is longer than eight characters,
+* the lower byte of the cluster number replaces the last two
+* characters to avoid name clashes. In any other case, it is your
+* responsibility to avoid name clashes.
+*
+* \param[in] parent The handle of the directory in which to create the file.
+* \param[in] file The name of the file to create.
+* \param[out] dir_entry The directory entry to fill for the new (or existing) file.
+* \returns 0 on failure, 1 on success, 2 if the file already existed.
+* \see fat_delete_file
+*/
+uint8_t fat_create_file(struct fat_dir_struct* parent, const char* file, struct fat_dir_entry_struct* dir_entry)
+{
+if(!parent || !file || !file[0] || !dir_entry)
+return 0;
+/* check if the file already exists */
+while(1)
+{
+if(!fat_read_dir(parent, dir_entry))
+break;
+if(strcmp(file, dir_entry->long_name) == 0)
+{
+fat_reset_dir(parent);
+return 2;
+}
+}
+struct fat_fs_struct* fs = parent->fs;
+/* prepare directory entry with values already known */
+memset(dir_entry, 0, sizeof(*dir_entry));
+strncpy(dir_entry->long_name, file, sizeof(dir_entry->long_name) - 1);
+/* find place where to store directory entry */
+if(!(dir_entry->entry_offset = fat_find_offset_for_dir_entry(fs, parent, dir_entry)))
+return 0;
+/* write directory entry to disk */
+if(!fat_write_dir_entry(fs, dir_entry))
+return 0;
+return 1;
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_file
+* Deletes a file or directory.
+*
+* If a directory is deleted without first deleting its
+* subdirectories and files, disk space occupied by these
+* files will get wasted as there is no chance to release
+* it and mark it as free.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in] dir_entry The directory entry of the file to delete.
+* \returns 0 on failure, 1 on success.
+* \see fat_create_file
+*/
+uint8_t fat_delete_file(struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry)
+{
+if(!fs || !dir_entry)
+return 0;
+/* get offset of the file's directory entry */
+offset_t dir_entry_offset = dir_entry->entry_offset;
+if(!dir_entry_offset)
+return 0;
+#if FAT_LFN_SUPPORT
+uint8_t buffer[12];
+while(1)
+{
+/* read directory entry */
+if(!fs->partition->device_read(dir_entry_offset, buffer, sizeof(buffer)))
+return 0;
+/* mark the directory entry as deleted */
+buffer[0] = FAT_DIRENTRY_DELETED;
+/* write back entry */
+if(!fs->partition->device_write(dir_entry_offset, buffer, sizeof(buffer)))
+return 0;
+/* check if we deleted the whole entry */
+if(buffer[11] != 0x0f)
+break;
+dir_entry_offset += 32;
+}
+#else
+/* mark the directory entry as deleted */
+uint8_t first_char = FAT_DIRENTRY_DELETED;
+if(!fs->partition->device_write(dir_entry_offset, &first_char, 1))
+return 0;
+#endif
+/* We deleted the directory entry. The next thing to do is
+* marking all occupied clusters as free.
+*/
+return (dir_entry->cluster == 0 || fat_free_clusters(fs, dir_entry->cluster));
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_file
+* Moves or renames a file.
+*
+* Changes a file's name, optionally moving it into another
+* directory as well. Before calling this function, the
+* target file name must not exist. Moving a file to a
+* different filesystem (i.e. \a parent_new doesn't lie on
+* \a fs) is not supported.
+*
+* After successfully renaming (and moving) the file, the
+* given directory entry is updated such that it points to
+* the file's new location.
+*
+* \note The notes which apply to fat_create_file() also
+* apply to this function.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in,out] dir_entry The directory entry of the file to move.
+* \param[in] parent_new The handle of the new parent directory of the file.
+* \param[in] file_new The file's new name.
+* \returns 0 on failure, 1 on success.
+* \see fat_create_file, fat_delete_file, fat_move_dir
+*/
+uint8_t fat_move_file(struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry, struct fat_dir_struct* parent_new, const char* file_new)
+{
+if(!fs || !dir_entry || !parent_new || (file_new && !file_new[0]))
+return 0;
+if(fs != parent_new->fs)
+return 0;
+/* use existing file name if none has been specified */
+if(!file_new)
+file_new = dir_entry->long_name;
+/* create file with new file name */
+struct fat_dir_entry_struct dir_entry_new;
+if(!fat_create_file(parent_new, file_new, &dir_entry_new))
+return 0;
+/* copy members of directory entry which do not change with rename */
+dir_entry_new.attributes = dir_entry->attributes;
+#if FAT_DATETIME_SUPPORT
+dir_entry_new.modification_time = dir_entry->modification_time;
+dir_entry_new.modification_date = dir_entry->modification_date;
+#endif
+dir_entry_new.cluster = dir_entry->cluster;
+dir_entry_new.file_size = dir_entry->file_size;
+/* make the new file name point to the old file's content */
+if(!fat_write_dir_entry(fs, &dir_entry_new))
+{
+fat_delete_file(fs, &dir_entry_new);
+return 0;
+}
+/* delete the old file, but not its clusters, which have already been remapped above */
+dir_entry->cluster = 0;
+if(!fat_delete_file(fs, dir_entry))
+return 0;
+*dir_entry = dir_entry_new;
+return 1;
+}
+#endif
+#if DOXYGEN || FAT_WRITE_SUPPORT
+/**
+* \ingroup fat_dir
+* Creates a directory.
+*
+* Creates a directory and obtains its directory entry.
+* If the directory to create already exists, its
+* directory entry will be returned within the dir_entry
+* parameter.
+*
+* \note The notes which apply to fat_create_file() also
+* apply to this function.
+*
+* \param[in] parent The handle of the parent directory of the new directory.
+* \param[in] dir The name of the directory to create.
+* \param[out] dir_entry The directory entry to fill for the new directory.
+* \returns 0 on failure, 1 on success.
+* \see fat_delete_dir
+*/
+uint8_t fat_create_dir(struct fat_dir_struct* parent, const char* dir, struct fat_dir_entry_struct* dir_entry)
+{
+if(!parent || !dir || !dir[0] || !dir_entry)
+return 0;
+/* check if the file or directory already exists */
+while(fat_read_dir(parent, dir_entry))
+{
+if(strcmp(dir, dir_entry->long_name) == 0)
+{
+fat_reset_dir(parent);
+return 0;
+}
+}
+struct fat_fs_struct* fs = parent->fs;
+/* allocate cluster which will hold directory entries */
+cluster_t dir_cluster = fat_append_clusters(fs, 0, 1);
+if(!dir_cluster)
+return 0;
+/* clear cluster to prevent bogus directory entries */
+fat_clear_cluster(fs, dir_cluster);
+memset(dir_entry, 0, sizeof(*dir_entry));
+dir_entry->attributes = FAT_ATTRIB_DIR;
+/* create "." directory self reference */
+dir_entry->entry_offset = fs->header.cluster_zero_offset +
+(offset_t) (dir_cluster - 2) * fs->header.cluster_size;
+dir_entry->long_name[0] = '.';
+dir_entry->cluster = dir_cluster;
+if(!fat_write_dir_entry(fs, dir_entry))
+{
+fat_free_clusters(fs, dir_cluster);
+return 0;
+}
+/* create ".." parent directory reference */
+dir_entry->entry_offset += 32;
+dir_entry->long_name[1] = '.';
+dir_entry->cluster = parent->dir_entry.cluster;
+if(!fat_write_dir_entry(fs, dir_entry))
+{
+fat_free_clusters(fs, dir_cluster);
+return 0;
+}
+/* fill directory entry */
+strncpy(dir_entry->long_name, dir, sizeof(dir_entry->long_name) - 1);
+dir_entry->cluster = dir_cluster;
+/* find place where to store directory entry */
+if(!(dir_entry->entry_offset = fat_find_offset_for_dir_entry(fs, parent, dir_entry)))
+{
+fat_free_clusters(fs, dir_cluster);
+return 0;
+}
+/* write directory to disk */
+if(!fat_write_dir_entry(fs, dir_entry))
+{
+fat_free_clusters(fs, dir_cluster);
+return 0;
+}
+return 1;
+}
+#endif
+/**
+* \ingroup fat_dir
+* Deletes a directory.
+*
+* This is just a synonym for fat_delete_file().
+* If a directory is deleted without first deleting its
+* subdirectories and files, disk space occupied by these
+* files will get wasted as there is no chance to release
+* it and mark it as free.
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in] dir_entry The directory entry of the directory to delete.
+* \returns 0 on failure, 1 on success.
+* \see fat_create_dir
+*/
+#ifdef DOXYGEN
+uint8_t fat_delete_dir(struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry);
+#endif
+/**
+* \ingroup fat_dir
+* Moves or renames a directory.
+*
+* This is just a synonym for fat_move_file().
+*
+* \param[in] fs The filesystem on which to operate.
+* \param[in,out] dir_entry The directory entry of the directory to move.
+* \param[in] parent_new The handle of the new parent directory.
+* \param[in] dir_new The directory's new name.
+* \returns 0 on failure, 1 on success.
+* \see fat_create_dir, fat_delete_dir, fat_move_file
+*/
+#ifdef DOXYGEN
+uint8_t fat_move_dir(struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry, struct fat_dir_struct* parent_new, const char* dir_new);
+#endif
+#if DOXYGEN || FAT_DATETIME_SUPPORT
+/**
+* \ingroup fat_file
+* Returns the modification date of a file.
+*
+* \param[in] dir_entry The directory entry of which to return the modification date.
+* \param[out] year The year the file was last modified.
+* \param[out] month The month the file was last modified.
+* \param[out] day The day the file was last modified.
+*/
+void fat_get_file_modification_date(const struct fat_dir_entry_struct* dir_entry, uint16_t* year, uint8_t* month, uint8_t* day)
+{
+if(!dir_entry)
+return;
+*year = 1980 + ((dir_entry->modification_date >> 9) & 0x7f);
+*month = (dir_entry->modification_date >> 5) & 0x0f;
+*day = (dir_entry->modification_date >> 0) & 0x1f;
+}
+#endif
+#if DOXYGEN || FAT_DATETIME_SUPPORT
+/**
+* \ingroup fat_file
+* Returns the modification time of a file.
+*
+* \param[in] dir_entry The directory entry of which to return the modification time.
+* \param[out] hour The hour the file was last modified.
+* \param[out] min The min the file was last modified.
+* \param[out] sec The sec the file was last modified.
+*/
+void fat_get_file_modification_time(const struct fat_dir_entry_struct* dir_entry, uint8_t* hour, uint8_t* min, uint8_t* sec)
+{
+if(!dir_entry)
+return;
+*hour = (dir_entry->modification_time >> 11) & 0x1f;
+*min = (dir_entry->modification_time >> 5) & 0x3f;
+*sec = ((dir_entry->modification_time >> 0) & 0x1f) * 2;
+}
+#endif
+#if DOXYGEN || (FAT_WRITE_SUPPORT && FAT_DATETIME_SUPPORT)
+/**
+* \ingroup fat_file
+* Sets the modification time of a date.
+*
+* \param[in] dir_entry The directory entry for which to set the modification date.
+* \param[in] year The year the file was last modified.
+* \param[in] month The month the file was last modified.
+* \param[in] day The day the file was last modified.
+*/
+void fat_set_file_modification_date(struct fat_dir_entry_struct* dir_entry, uint16_t year, uint8_t month, uint8_t day)
+{
+if(!dir_entry)
+return;
+dir_entry->modification_date =
+((year - 1980) << 9) |
+((uint16_t) month << 5) |
+((uint16_t) day << 0);
+}
+#endif
+#if DOXYGEN || (FAT_WRITE_SUPPORT && FAT_DATETIME_SUPPORT)
+/**
+* \ingroup fat_file
+* Sets the modification time of a file.
+*
+* \param[in] dir_entry The directory entry for which to set the modification time.
+* \param[in] hour The year the file was last modified.
+* \param[in] min The month the file was last modified.
+* \param[in] sec The day the file was last modified.
+*/
+void fat_set_file_modification_time(struct fat_dir_entry_struct* dir_entry, uint8_t hour, uint8_t min, uint8_t sec)
+{
+if(!dir_entry)
+return;
+dir_entry->modification_time =
+((uint16_t) hour << 11) |
+((uint16_t) min << 5) |
+((uint16_t) sec >> 1) ;
+}
+#endif
+/**
+* \ingroup fat_fs
+* Returns the amount of total storage capacity of the filesystem in bytes.
+*
+* \param[in] fs The filesystem on which to operate.
+* \returns 0 on failure, the filesystem size in bytes otherwise.
+*/
+offset_t fat_get_fs_size(const struct fat_fs_struct* fs)
+{
+if(!fs)
+return 0;
+#if FAT_FAT32_SUPPORT
+if(fs->partition->type == PARTITION_TYPE_FAT32)
+return (offset_t) (fs->header.fat_size / 4 - 2) * fs->header.cluster_size;
+else
+#endif
+return (offset_t) (fs->header.fat_size / 2 - 2) * fs->header.cluster_size;
+}
+/**
+* \ingroup fat_fs
+* Returns the amount of free storage capacity on the filesystem in bytes.
+*
+* \note As the FAT filesystem is cluster based, this function does not
+*       return continuous values but multiples of the cluster size.
+*
+* \param[in] fs The filesystem on which to operate.
+* \returns 0 on failure, the free filesystem space in bytes otherwise.
+*/
+offset_t fat_get_fs_free(const struct fat_fs_struct* fs)
+{
+if(!fs)
+return 0;
+uint8_t fat[32];
+struct fat_usage_count_callback_arg count_arg;
+count_arg.cluster_count = 0;
+count_arg.buffer_size = sizeof(fat);
+offset_t fat_offset = fs->header.fat_offset;
+uint32_t fat_size = fs->header.fat_size;
+while(fat_size > 0)
+{
+uintptr_t length = UINTPTR_MAX - 1;
+if(fat_size < length)
+length = fat_size;
+if(!fs->partition->device_read_interval(fat_offset,
+fat,
+sizeof(fat),
+length,
+#if FAT_FAT32_SUPPORT
+(fs->partition->type == PARTITION_TYPE_FAT16) ?
+fat_get_fs_free_16_callback :
+fat_get_fs_free_32_callback,
+#else
+fat_get_fs_free_16_callback,
+#endif
+&count_arg
+)
+)
+return 0;
+fat_offset += length;
+fat_size -= length;
+}
+return (offset_t) count_arg.cluster_count * fs->header.cluster_size;
+}
+/**
+* \ingroup fat_fs
+* Callback function used for counting free clusters in a FAT.
+*/
+uint8_t fat_get_fs_free_16_callback(uint8_t* buffer, offset_t offset, void* p)
+{
+struct fat_usage_count_callback_arg* count_arg = (struct fat_usage_count_callback_arg*) p;
+uintptr_t buffer_size = count_arg->buffer_size;
+for(uintptr_t i = 0; i < buffer_size; i += 2, buffer += 2)
+{
+uint16_t cluster = read16(buffer);
+if(cluster == HTOL16(FAT16_CLUSTER_FREE))
+++(count_arg->cluster_count);
+}
+return 1;
+}
+#if DOXYGEN || FAT_FAT32_SUPPORT
+/**
+* \ingroup fat_fs
+* Callback function used for counting free clusters in a FAT32.
+*/
+uint8_t fat_get_fs_free_32_callback(uint8_t* buffer, offset_t offset, void* p)
+{
+struct fat_usage_count_callback_arg* count_arg = (struct fat_usage_count_callback_arg*) p;
+uintptr_t buffer_size = count_arg->buffer_size;
+for(uintptr_t i = 0; i < buffer_size; i += 4, buffer += 4)
+{
+uint32_t cluster = read32(buffer);
+if(cluster == HTOL32(FAT32_CLUSTER_FREE))
+++(count_arg->cluster_count);
+}
+return 1;
+}
+#endif

Mercurial > pihelp

comparison fat.c @ 19:5f9a40d6991b